U.S. Population Density when the 300 million mark was met (an unclassed map): http://earthobservatory.nasa.gov/IOTD/view.php?id=7052
The United States of Mind (go to the Interactive Map): http://online.wsj.com/article/SB122211987961064719.html?mod=yhoofront#project
Gas Price Map: http://www.gasbuddy.com/gb_gastemperaturemap.aspx
Electoral Shifts from 2004: http://www.nytimes.com/interactive/2008/11/05/us/politics/20081104_ELECTION_R...
Life Expectancy Across the US: http://www.washingtonpost.com/wp-srv/special/nation/life-expectancy-map/
US Population and Growth Trends: http://3.bp.blogspot.com/_RBw-psMN_Ew/S-2DPSCCzoI/AAAAAAAAHjI/TeRzMDtrFrA/s16...
Increasing Girth Rate: http://www.washingtonpost.com/wp-dyn/content/graphic/2010/09/20/GR20100920068...
Greendex: http://environment.nationalgeographic.com/environment/greendex/
Census Data in US since 1990: http://www.washingtonpost.com/wp-srv/special/nation/census/2010/